OSP

OSP offers high-level technical expertise and unparalleled access to application experience, support and product recommendations for energy and industrial applications. With offices in Alberta and Texas, we partner with our clients to provide microbial identification and control solutions. Our products include LifeCheck®, 2K7® Biocide and Telomer®.

Brands: 2K7®
LifeCheck®
Telomer®

Press Releases

Background

Premature coiled tubing (CT) unit failure has been observed in certain areas of the United States, such as the Eagle Ford and Haynesville formations, and the Permian basin in Texas. This issue was not thought to be as prevalent in Canada until a recent Society of Petroleum Engineers (SPE) publication detailed how a major Canadian CT service company experienced an alarming seven CT string failures within three months while performing bridge plug mill-out operations in the northeastern British Columbia portion of the Montney formation.1

The CT string point of failures were in the range of 18 – 48% fatigue – well below their predicted fatigue life. CT strings can fail for a variety of reasons including external mechanical damage, corrosion and excessive diametrical growth. Premature CT failure results not only in operational delays with the associated cost, but critical safety risks are posed to personnel on location.

Challenge

Third party analysis indicated that these CT string failures manifested in the form of pinholes and corrosion, primarily at the bias weld. The filler material used in bias welds has different mechanical properties than the base pipe material, making it weaker and more prone to fatigue. To determine the mechanism of failure, CT string and fluid samples from four of the seven units were further analyzed.

This analysis revealed internal corrosion pitting in both the base and filler material and extremely high concentrations of bacteria in the source water (>107). The presence of both sulfate reducing bacteria (SRB) and acid producing bacteria (APB) was indicated in the fluid and on the solid metal using the OSP LifeCheck™ SRB Indicator Kit and LifeCheck PRD Kit, respectively. These bacterial subtypes are known to be related to microbial influenced corrosion (MIC). MIC is caused by the formation of biofilms resulting in localized pitting corrosion, which leads to micro-cracks and eventual pipe failure.

Solution

The CT service company undertook laboratory and field studies to evaluate available biocides with the goal of creating an optimized treatment program. Multiple field water samples were subjected to biocide kill and loading studies to determine efficacy and optimal concentrations. Field studies were then performed to confirm the laboratory results and establish the treatment regime as well as the bacterial contribution from source fluid versus wellbore flowback.

Bacterial levels were monitored using the OSP LifeCheck ATP Test Kit, which measures the metabolic activity of living cells through quantification of ATP (adenosine triphosphate) levels in fluid. Four biocides were evaluated: glutaraldehyde, 2,2-dibromo-3-nitrilopropionamide (DBNPA), tetrakis(hydroxymethyl) phosphonium sulfate (THPS) and OSP 2K7®. Because each compound has a different mode of action, biocides were tested at the same concentration. Once comparative efficacy was evaluated, optimal treatment level was determined.

Laboratory Results

The laboratory analysis showed that while all biocides were initially effective at reducing bacterial levels, the glutaraldehyde and THPS effects were short-lived with levels rebounding after one day. The 2K7 and DBNPA biocides were further evaluated over a range of ppm values. Even at the highest concentration tested, the DBNPA showed bacterial population recovery at 2 weeks, with lower concentrations rebounding in less than a week.

The 2K7 biocide was effective at 100 ppm for 8 days – twice as long as the DBNPA at the same concentration – and at >200 ppm reduced bacterial levels for 2 weeks. 2K7 biocide works by disrupting the activity of bacterial membrane proteins causing cellular collapse. Unlike other biocides, which can react with friction reducers negating the effect of both, 2K7 is nonionic and does not react with other fluid additives.

Field Results

Field studies conducted on three separate well pads showed that one 2K7 Water Soluble Pak (WSP) per 10 m3 (63 bbl) surface water effectively reduced bacterial levels from >106 to<104 with agitation of the fluid reducing the reaction time. This fluid was then used for CT bridge plug milling operations and bacteria levels monitored at various fluid locations in the closed loop throughout the operations.

Evaluation of flowback from the wellbore indicated consistently lower bacterial concentrations than the injected surface water. Despite this, bacteria levels at surface were rebounding. Therefore, the observed increases in surface bacteria were due to the population rebounding while sitting in the surface tanks.

This rebound effect was because the CT fluid for the mill-out operations was reused for each successive pad well. As flowback water was introduced into the surface tanks, so were the additives (polymers, surfactants) from stimulation operations that, along with dissolved formation nutrients (sulfates, nitrates, phosphates) and increased temperatures, provided an ideal environment for bacterial regrowth.

The ability to identify the source of bacterial population rebound in real-time using the OSP LifeCheck ATP Test Kit enabled implementation of lower, maintenance treatments of the surface water with 2K7 biocide (one WSP per 40 – 100 m3 fluid every 12 – 24 hr). In addition, pre-storage treatment of the CT unit has been implemented as the standard operating procedure by the CT service company. Since the treatment program, no additional CT string failures associated with MIC have been recorded.

Mitigation of premature string failures due to microbial influenced corrosion

Background

Coiled tubing (CT) is used for a variety of operations in oil and gas wells, including mill out of bridge plugs after cemented liner plug-and-perf stimulation. With each trip in or out of the wellbore, the CT string incurs a certain amount of fatigue that can be estimated using simulation software based on the CT outside diameter (OD) and material grade. CT units are retired at 80% of predicted fatigue. CT manufacturers have increasing empirical evidence showing that CT units experience premature string failures (below 80% fatigue) in certain areas, such as the Eagle Ford, Haynesville formations and Permian basin in Texas, and the Horn River and Montney formations in northern British Columbia. These string failures manifest in the form of pinholes and parting of the pipe. If these failures occur above ground, safety risks are a major concern. If they occur downhole, as detected by a sudden drop in tubing weight, the project is delayed and the costs of fishing out the broken pipe is incurred as well as the loss of the CT unit for future operations.

Challenge

A CT service company, Pioneer Energy Services, working for an operator in the volatile oil window of the Eagle Ford formation was experiencing premature coiled tubing string failures. Recent conference paper presentations have pointed to microbial influenced corrosion (MIC) as a cause of premature CT failure1,2,3. MIC is caused by the formation of biofilms resulting in localized corrosion in the form of very small pits, which lead to cracks and eventual pipe failure. The base fluid used forCT operations is often produced water recycled multiple times from stimulation operations. This fluid provides an ideal environment for bacterial growth in that it contains hydrocarbon and energy sources (polymers, surfactants), is in the range of 15-35°C (60-95°F) and is stagnant when stored in tanks.1,2,3

Treatment

The CT unit was 2 3/8-in. with 21,000 ft total length, and a capacity of 85 bbl. The total fluid volume in the on-site tanks was 2,500 bbl, with the CT unit pumping 3.5 bbl/min at 7,000 psi. A mixing plant was on-site, which fed the pump truck, and in turn fed the CT unit. When the fluid came back up from the wellbore, it was discharged into a 109 bbl open top tank, which pumped into the first of five fractionation tanks that were connected in series. It was determined that the best place to apply 2K7 WSP would be nearest the discharge into the open top tank.

LifeCheck ATP Test Kit software was installed on the CT unit computer and calibrated prior to sampling. A 2 ml sample was taken from the mixing plant and resulted in a count of 9,235 pg/ml ATP. This was equivalent to 6 bottle growth (106) using conventional serial dilution test kits. The water had a distinct odor of bacteria and sulfur. A second test was done using the same standard with 3 ml of sample. The result was 12,010 pg/ml ATP. This was also equivalent to 7 bottle growth (107).

Due to the unusually high level of bacteria, it was recommended to shock treat the fluid with 2K7 WSP. This was done by adding four boxes (25 x 1 kg paks per box) of 2K7 WSP to the open water tank.

2K7 Biocide

Volume of Fluid

Treatment Level

1 pak (1 kg/2.2 lb)

10 m3/63 bbl

100 ppm

4 paks (4 kg/8.8 lb)

40 m3/250 bbl

100 ppm

1 box (25 kg/55 lb)

250 m3/1,575 bbl

100 ppm

Results

A fluid sample was tested using LifeCheck ATP ~12 hours later and measured at 147 pg/ml ATP. Therefore, the shock treatment with 2K7 WSP successfully reduced the bacterial load. In addition to the reduction in bacteria, Pioneer communicated that circulating pressure was reduced from 7,200 psi to 5,750 psi on average at the same rate of 3.5 bbl/min. Circulating pressure did increase later on, but Pioneer concluded that it was most likely due to increasing chloride and solids within the fluid. OSP suggested that Pioneer monitor with LifeCheck ATP every 2 hours and treat with 1 box every 6-8 hours when the ATP count was >400 pg/ml. The goal was to remain below 500 pg/ml.

Pioneer continued to use 2K7 WSP on a second CT mill-out job on the same well pad. The second well used the same water as the first, but it started off at a lower bacterial load due to the previous treatment. A sample tested before offloading the fluid from the truck had 1536 pg/ml ATP. LifeCheck ATP numbers rose when freshwater was added to dilute the solids in the fluid. They treated the 2,800 bbl total volume with 1 box of 2K7 WSP, which brought the numbers down to 78 pg/ml ATP. However, freshwater continued to be added, which with the combination of produced water from the wellbore, brought the numbers back up to 607 pg/ml ATP, indicating the need for continued maintenance treatments.

The reduction in bacterial count using 2K7 WSP mitigates MIC, the cause of premature CT string failure. At the completion of each job, prior to CT transport to another job location or storage, treatment with 2K7 Bugstick, a solid stick format, is performed for extended control to preserve the CT steel. Based on this successful trial, Pioneer plans to continue using the combination of OSP’s LifeCheck ATP Test Kit and 2K7 WSP for CT mill-outs and other applications including pre-stimulation toe prep operations.

Background

Coiled tubing (CT) mill out of bridge plugs is a common operation. To increase the lifespan of their tubing, Service Companies are turning to a variety of products to mitigate microbiologically influenced corrosion (MIC), which has been shown to cause pitting leading to premature string failure1. Microbial growth in mill-out fluids pumped downhole can also cause formation damage, such as souring.

Challenge

A variety of biocide actives are available on the market, each with a unique performance range based on their chemistry2. Creating a comprehensive biocide treatment program for a particular application requires an understanding of these characteristics. For this reason, CT service companies are turning to chemical providers such as OSP to provide expertise for both testing and treatment of microbial contamination.

Study

A US Service Company approached OSP to assist in the determination of the best chemistry to provide long-term microbial control for their CT mill-out operations. They chose 2 horizontal wells on the same pad in the Eagle Ford formation. Two CT units were used, such that one fluid system could be treated with the current product, and the other with OSP 2K7 Water Soluble Paks (WSP).

In all cases, the milling fluid was pretreated on location by the water supplier with a glutaraldehyde-quaternary ammonium (Glut-Quat) combination biocide compound at 5 gal per 500 bbl tank. The Service Company then treated the fluid for one well with their current product, which was added on-the-fly at 250 ppm, and the other with 2K7 WSP added to the surface tanks.

OSP also provided onsite LifeCheck™ Microbial Services (LMS) to test fluid samples taken from surface tanks at various time points during the operation. The OSP LifeCheck ATP Test Kit was used to rapidly measure total microbial levels in real-time through quantification of ATP (adenosine triphosphate)3. ATP levels are expressed in pg/ml and indicate the metabolic activity of living cells, enabling accurate measurement of total microbial content. Guidelines for ATP levels and required treatment in this application are provided in Table 2 within the PDF.

Results

The LifeCheck ATP test kit results during and after mill-out operations is shown in Figures 1 and 2 within the PDF. In both the main and return tanks, the well treated with 2K7 WSP maintained ATP levels below 50 pg/ml; whereas, ATP levels in the well treated with the current product spiked to 129 pg/ml and 1,380 pg/ml in the main and return tanks, respectively. These results indicate that the current product was unable to provide long-term microbial control compared to treatment with 2K7 WSP.

Products

2K7® Solution

Liquid delivery system used for in-line mixing where a liquid format is preferred to expedite biocide action as no dissolving is required.... More Info Less Info

2K7® is a broad-spectrum biocide that has been effectively used as an antimicrobial and preservative in many industries for over 30 years. OSP 2K7 Biocides can solve your microbial contamination – no matter what the application.

2K7 Biocide Features and Benefits

Broad spectrum antimicrobial

No known resistance

Fast-acting, long-term control

Non-toxic and biodegradable

Compatible with most chemistries (non-ionic, non-foaming)

Effective in fluids with high total suspended solids (non-surfactant)

Effective in high brines, high iron and sour service (H2S)

Stable in solid and solution form

How 2K7 Biocide Works

2K7 biocides work by incorporating into sulfur-containing proteins found in bacteria and disrupting their activity. The antimicrobial activity is not associated with bromine or formaldehyde. OSP offers several formats and formulations of 2K7 depending on the application.

For more information and to review our Biocide Selection Guide visit our website.

2K7® is a broad-spectrum biocide that has been effectively used as an antimicrobial and preservative in many industries for over 30 years. OSP 2K7 Biocides can solve your microbial contamination – no matter what the application.

2K7 Biocide Features and Benefits

Broad spectrum antimicrobial

No known resistance

Fast-acting, long-term control

Non-toxic and biodegradable

Compatible with most chemistries (non-ionic, non-foaming)

Effective in fluids with high total suspended solids (non-surfactant)

Effective in high brines, high iron and sour service (H2S)

Stable in solid and solution form

How 2K7 Biocide Works

2K7 biocides work by incorporating into sulfur-containing proteins found in bacteria and disrupting their activity. The antimicrobial activity is not associated with bromine or formaldehyde. OSP offers several formats and formulations of 2K7 depending on the application.

For more information and to review our Biocide Selection Guide vist our website.

2K7® Granular

Crystal format, providing a concentrated solid as loose granules. Now available in Canada.... More Info Less Info

2K7® is a broad-spectrum biocide that has been effectively used as an antimicrobial and preservative in many industries for over 30 years. OSP 2K7 Biocides can solve your microbial contamination – no matter what the application.

2K7 Biocide Features and Benefits

Broad spectrum antimicrobial

No known resistance

Fast-acting, long-term control

Non-toxic and biodegradable

Compatible with most chemistries (non-ionic, non-foaming)

Effective in fluids with high total suspended solids (non-surfactant)

Effective in high brines, high iron and sour service (H2S)

Stable in solid and solution form

How 2K7 Biocide Works

2K7 biocides work by incorporating into sulfur-containing proteins found in bacteria and disrupting their activity. The antimicrobial activity is not associated with bromine or formaldehyde. OSP offers several formats and formulations of 2K7 depending on the application.

For more information and to review our Biocide Selection Guide vist our website.